Functional Material for Acoustic Equipment

ABSTRACT

[Object] To provide the functional material for acoustic equipment of this invention made by molding and curing the resin composition consisting of a thermosetting resin and a filler shows superior sound performance to the conventional material. 
     [Means to Resolve] The functional material for acoustic equipment made by molding the resin composition consisting of the thermosetting resin and the filler, where a specific gravity of the molded material is between 1.5 and 5.0, the porosity of the molded materials is between 2% and 20%, and the average pore size of the materials is between 0.1 μm and 3.0 μm. The resin composition has 5-25 weight % of the thermosetting resin relative to the entire amount of the resin compositions and the filler of the resin composition partially includes 10-35 weight % of the porous filler (preferably having micro porous structure) relative to the entire resin composition.

This invention relates to a functional material made by molding a resin composition, which is preferable for a functional material used for an acoustic equipment. This application claims priority to previously filed U.S. Provisional patent application No. 61/938,866 filed on 2014 Apr. 12 and the contents of which is incorporated herewith.

BACKGROUND OF THE INVENTION Field of the Invention

Generally, as a functional material for acoustic equipment, a material has an internal loss like wood to absorb unnecessary external vibration, and a high rigidity and a high specific gravity to avoid unnecessary resonance of itself due to the external vibration without attenuating necessary vibration.

As the material described above, a material made by molding a resin composition consisting of a thermosetting resin and inorganic fillers have been invented.

The Patent Document 1 discloses a resin composition to make a material for acoustic equipment by molding that includes a thermosetting resin and an inorganic filler and is characterized that the inorganic filler partially or entirely is in a needle shape with 1-20 μm particle size measured by the sedimentation method.

The Patent Document 2 discloses a thermosetting resin composition for acoustic equipment characterized that the filler composed of 60-90 weight % of a heavy calcium carbonate with 250-10 μm particle size and 10-40 weight % of an inorganic powder with 8-0.1 μm particle size are added to a phenol resin in the ratio of 35-80 weight % relative to the entire amount to be mixed, kneaded, and crushed.

The Patent Document 3 discloses a resin composition to make a structural material for acoustic equipment by molding characterized that a resin composition includes a thermosetting resin, a curing agent, an inorganic filler, and a fiber reinforcing material and an aromatic polyamide fiber is used for the fiber reinforcing material.

The Patent Document 4 discloses a resin composition to make a material for acoustic equipment by molding characterized that a resin composition includes a thermosetting resin and an inorganic filler and that a part or entire inorganic filler is an amorphous inorganic small short fiber.

The Patent Document 5 discloses a resin composition to make a material for the acoustic equipment by molding characterized that a resin composition does not include a thermosetting resin and an inorganic filler but a reactive liquid rubber is added therein.

These materials have internal losses equal to wood and to rigidity and a specific gravity are high, which are designed to provide a better acoustic property; however, a further development on these materials is on demand.

PRIOR ARTS Patent Documents

[Patent Document 1] Japanese Provisional Patent Publication No. 1983-53952

[Patent Document 2] Japanese Provisional Patent Publication No. 1983-89644

[Patent Document 3] Japanese Provisional Patent Publication No. 1983-104949

[Patent Document 4] Japanese Provisional Patent Publication No. 1983-215433

[Patent Document 5] Japanese Provisional Patent Publication No. 1984-30858

SUMMARY OF THE INVENTION Problems to be Resolved by the Invention

It is an object of this invention to provide a functional material for acoustic equipment by molding and curing resin compositions, which eliminates unpleasant and uncomfortable low frequency vibration but provides, comparing to the conventional materials, more preferable acousticity such as a comfortable natural sound, high and low sound area expansion, and depth of sound.

Means to Resolve the Problems

The resin compositions made from such as the thermosetting resin and inorganic filler have innumerable communicating minute pores inside.

The inventors diligently investigated, as assuming that the necessary vibration attenuation occurs due to viscous resistance of the air involved in the pores, and found that the functional material for acoustic equipment with more superior acoustic performance than the conventional materials can be obtained by maintaining the porosity of the molded materials and the average pore size within a predetermined range.

This invention relates to the functional material for acoustic equipment made by molding the resin compositions suitable for the functional material used for acoustic equipment and is based on the following technology.

(1) The functional material for acoustic equipment made by molding the resin compositions composed of the thermosetting resin and filler is such that the specific gravity of the molded material is between 1.5 and 5.0, the porosity is between 2-20%, and the average pore size of 0.1-3 μm.

(2) The functional material for acoustic equipment as described in (1), where the above-resin compositions include the thermosetting resin of 5-25 weigh % relative to the entire amount of the resin composition.

(3) The functional material for acoustic equipment as described in the above (1) or (2), where the above-resin compositions include the filler partially involving porous filler of 10-35 weight % relative to the entire amount of resin compositions.

(4) The functional material for acoustic equipment as described in the above (3), where the porous filler has a micro porous structure.

(5) The functional material for acoustic equipment as described in the above (4), where the filler having the micro porous structure is one or more selected from a group of zeolite, activated carbon, porous silica, or porous alumina.

ADVANTAGES OF THE INVENTION

This invention can provide the functional material for acoustic equipment made by molding and curing the resin compositions composed of the thermosetting resin and the filler that provides more preferable acoustic performance than the conventional materials, such performance including such as maintenance of the preferable moldability, elimination of uncomfortable low frequency vibration, creation of the comfortable natural sound, high and low sound areas expansion, and creation of depth of sound.

EMBODIMENTS OF THE INVENTION

The functional material for acoustic equipment of this invention is characterized that the functional material is made by molding the resin compositions composed of the thermosetting resin and filler and has the molded material specific gravity of 1.5-5.0, the porosity of 2-20%, and the average pore size of 0.1-3.0 μm.

By arranging the specific gravity of the molded material 1.5-5.0, the porosity of the same 2-20%, and the average pore size of the same 0.1-3.0 μm, a chance of attenuating the necessary vibration is eliminated, thereby providing the functional material for acoustic equipment with superior acoustic performance.

The specific gravity of the material can be adjusted by selecting the type of the filler to be added to the resin compositions appropriately.

The porosity and the average pore size can be adjusted by changing the molding conditions such as the molding temperature, the molding pressure, and the molding time; however, an excessive consideration and examination of the molding conditions are necessary until preferable porosity and average pore size can be obtained.

Then, this invention resolved the problem by adding the porous filler of 10-35 weight % relative to the entire amount of the resin compositions as a part of the filler to the resin compositions.

By adding the porous filler having innumerable small pores, the molded article with desirable porosity and average pore size can be obtained, without excessive consideration of the molding pressure, by molding at the molding temperature between 130 and 170 centigrade, the molding pressure between 20 and 40 MPa, and the molding time between 2 and 15 minutes.

The porous filler can be a porous filler with a micro porous structure at 2 nm or less average pore diameter, a porous filler with a meso-porous structure at more than 2 nm but less than 50 nm average pore diameter, or a porous filler where the porous filler has a micro porous structure at 50 nm or more average pore diameter.

By using the porous filler with the micro porous structure, the amount of use of the porous filler is decreased and then flexibility to adjust the amount of addition of other fillers increases, therefore, it becomes easy for favorable thing to adjust the specific gravity.

The porous filer with the micro porous structure can be any one of or combination of zeolite, active carbon, porous silica, and porous alumina.

The specific gravity in this invention is used the value measured by Pycnometer and Hydrostatic Method, and the porosity and average pore size are used the values measured by Mercury Porosimeter using the test pieces cutting from the functional material for acoustic equipment.

The thermosetting resin can be one of or any combination of such as straight phenol resin, modified phenol resin modified by cashew oil, silicone oil, or various elastomers such as acrylic rubber, the aralkyl modified phenol resin formed by reacting phenol compounds, aralkyl ether compounds, and aldehyde compounds, and the thermosetting resin dispersing such as various elastomers and fluorine polymer in the phenol resin.

The thermosetting resin in the amount of 5-20 weight % relative to the entire resin compositions is added. If the amount of the thermosetting resin added therein is less than 5 weight %, the molded article tends to be cracked, and if the amount of the thermosetting resin added exceeds 25 weight %, a blister occurs in the molded article.

The filler other than the above-described porous filler can be one of or any combination of an organic fiber such as aramid fiber, PAN fiber, and cellulose fiber, an inorganic fiber such as glass fiber and rock wool, an inorganic particle such as calcium carbonate, sulfuric acid, barium, a mica, a talk, a wollastonite, a vermiculite, alumina, silica, zirconia, and zirconium silicate, a carbon particle such as coke and graphite, a rubber particle such as NBR particle and SBR particle, a particle or a short fiber made of metal such as copper, brass, bronze, aluminum, stainless steel, and steel.

The functional material for acoustic equipment of this invention is manufactured through steps of mixing the thermosetting resin and filler evenly into the predetermined amount of the resin compositions in a mixer, molding the mixture after placing the mixture in the predetermined shaped thermoforming mold to heat the same at 130-170 centigrade under the pressure of 20-40MPa for 2-15 minutes, and grinding the surface to make the predetermined roughness of the surface. In addition, as necessary, a perforating a bore for screw-engaging with acoustic equipment.

EMBODIMENTS

The following sections show the embodiments and comparative examples of this invention to concretely explain this invention; however, the following embodiments do not limit the scope of this invention.

Embodiments 1-6 and Comparative Examples 1 Manufacturing Method for the Functional Material for Acoustic Equipment

The resin compositions with the compositions described in Table 1 is mixed in a Loedige mixer for about 5 minutes, and after the obtained mixture is placed in the thermoforming mold to mold under the conditions described in Table 1, the resulted article is processed to be in 100 mm×55 mm×5 mm to obtain the functional material for acoustic equipment according to the comparative examples 1-5.

With respect to the functional material for acoustic equipment in the embodiments 1-6 and the comparative examples 1-5, the evaluation as to the physical property, the moldability, and the acoustic performance are conducted as below. The evaluation result is explained with Table 1.

Physical Property Evaluation. Specific gravity is determined by Pycnometer and Hydrostatic Method, and the porosity and the average pore size are determined by the Mercury Porosimeter (Yuasa lonicsCo., Ltd).

Moldability Evaluation. Moldability evaluation standard is described as follows:

-   -   ∘: no crack and blister     -   x: crack and blister

Acoustic Performance Evaluation. Acoustic performance evaluation is conducted in the acoustic audio room. The sound facilities include a power amplifier (Esoteric A-03), a D/A converter, an amplifier, a compact disc player (Esoteric K-05), and a large speaker (B&W 801D). The power amplifier, the D/A converter and the speaker that output analog signals and tend to show the sound quality variation easily are three point mounted (right, left, and back center) on the functional material for acoustic equipment according to the embodiments 1-6 and the comparative examples 1-5 are placed under. Here, the functional material is placed separately and independently under the power amplifier, the D/A converter, and the speaker.

Evolution points are (1) uncomfortable low frequency vibration by the influence of pores of the material and (2) comfortable natural sound by the influence of the specific gravity of the material relative to the sound frequency resonance in addition to the low pitched tone enhancement, feeling of sound depth, and high pitched tone enhancement.

An evaluating music having sound sources with different frequency emphasizing the instruments being used for the total evaluation.

-   -   Japanese popular music in 1970-1980's (vocal, guitar, bass         guitar, and drum: 30 Hz-18 kHz: center 400 Hz-3 kHz)     -   jazz music (piano: 30 Hz-5 kHz: center 200 Hz-1 kHz)     -   classical music (orchestral music: 100 Hz-4 kHz: center 300 Hz-2         kHz)     -   rock music (guitar, bass guitar, drum, keyboard Instrument: 40         Hz-18 kHz: center 100 Hz-1 kHz)

Evaluators are selected from a unisex group of 20 people aged between 22 and 62 with different tastes, and the results are based on the average of the evaluators' judges. The valuation basis of the acoustic performance are as follows:

⊚: 15-20 people judge it to be good

∘: 10-14 people judge it to be good

Δ: 5-9 people judge it to be good

x: 0-4 people judge it to be good

TABLE 1 Embodiments Comparative Examples 1 2 3 4 5 6 1 2 3 4 5 Composition Straight phenol 15.0 5.0 25.0 5.0 25.0 15.0 15.0 2.0 30.0 25.0 5.0 (Weight %) resin Aramid pulp 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 (ave. fiber diameter 1 μm, ave. fiber length 3 μm) Muscovite (ave. 10.0 10.0 10.0 3.0 30.0 10.0 10.0 10.0 10.0 3.0 3.0 fiber diameter 10 μm, ave. fiber length 200 μm) Brass fiber (ave. 25.0 25.0 20.0 45.0 0.0 25.0 25.0 25.0 25.0 0.0 45.0 fiber diameter 150 μm, ave. fiber length 3 μm) Cast iron 25.0 20.0 20.0 40.0 0.0 25.0 25.0 25.0 25.0 0.0 45.0 particle (ave. particle diameter 80 μm) NBR particle 0.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 70.0 0.0 (ave. particle diameter 90 μm) Active carbon 10.0 10.0 10.0 5.0 35.0 0.0 10.0 10.0 8.0 0.0 0.0 particle (ave. particle diameter 120 μm) Zeoite (ave. 0.0 0.0 0.0 0.0 0.0 10.0 0.0 0.0 0.0 0.0 0.0 particle diameter 6 μm) Calcium 13.0 23.0 13.0 0.0 8.0 13.0 13.0 26.0 0.0 0.0 0.0 carbonate (ave. particle diameter 6 μm) Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Molding Molding temp. 150 150 150 150 150 150 130 150 150 150 150 (° C.) Molding 30 30 30 30 30 30 3 30 30 30 30 pressure (MPa) Molding time 8 8 8 8 8 8 8 8 8 8 8 (minutes) Physical Specific gravity 2.9 2.7 2.5 4.3 1.8 2.8 2.5 3.1 2.6 1.1 5.4 Property Porosity (%) 5.0 15.0 2.0 20.0 10.0 6.0 25.0 20.0 1.0 0.3 5.0 Ave. pore size 0.4 1.5 0.1 3.0 0.3 0.5 1.3 5.0 0.1 0.1 0.9 (μm) Evaluation Moldability ◯ ◯ ◯ ◯ ◯ ◯ ◯ Δ Δ ◯ ◯ Result Uncomfortable ◯ ⊚ ◯ ◯ ⊚ ◯ X ◯ X ◯ Δ low frequency vibration (porosity) Comfortable ⊚ ⊚ ◯ ◯ ◯ ⊚ Δ X Δ X Δ natural sound (specific gravity, pore size) Low pitched ◯ ◯ ◯ ⊚ ⊚ ◯ Δ ◯ Δ Δ X tone enhancement (specific gravity, pore size) Feeling of ⊚ ◯ ◯ ◯ ◯ ⊚ Δ Δ Δ X Δ sound depth (specific gravity, pore size) High pitched ⊚ ⊚ ⊚ ⊚ ◯ ⊚ ◯ ◯ ◯ Δ X tone enhancement (specific gravity, pore size) ave. = average temp. = temperature

From the results in Table 1, maintaining the porosity and the specific gravity within the predetermined range reduces the unconformable low frequency vibration and provides the functional material for acoustic equipment with preferable sound performance such as comfortable natural sound, low pitched sound enhancement, sound depth feeling, and high pitched sound enhancement. Also, the material is superior in its moldability.

INDUSTRIAL APPLICABILITY

The functional material for acoustic equipment of this invention made by molding and curing the resin compositions composed of the thermosetting resin and the filler shows superior sound performance to the conventional material and is suitable for an audio board, an insulator (acoustic equipment foot, transformer vibration damping board, and speaker unit vibration damping board) , a tuning panel, an acoustic equipment box, an audio rack, and a speaker box material. 

What is claimed is:
 1. Functional material for acoustic equipment, which is a molded resin composition consisting of a thermosetting resin and a filler, wherein a specific gravity of the molded material is between 1.5 and 5.0, a porosity of the molded material is between 2% and 20%, and an average pore size of the material is between 0.1 μm and 3.0 μm.
 2. The functional material for acoustic equipment according to claim 1, wherein said resin composition has 5-25 weight % of the thermosetting resin relative to the entire amount of the resin composition.
 3. The functional material for acoustic equipment according to claim 1, wherein said filler of the resin composition partially includes 10-35 weight % of a porous filler relative to the entire resin composition.
 4. The functional material for acoustic equipment according to claim 3, wherein said porous filler has a micro porous structure.
 5. The functional material for acoustic equipment according to claim 4, wherein said porous filler with the micro porous structure is one or more selected from a group of zeolite, active carbon, porous silica, and porous alumina. 